Double-lift jack



May 1927. y

3 w. BAT: DOUBLE LIFT JAC Filed April 4. 1924 2 Shouts-Shoot 1 Paten'ted May 17, 1927.

UNITED STATES PTENT OFFICE.

JOHN W. BATE, OF RACINE, 'WISCONSIN.

:DOUBLE-IIFZlL` JACK.

Application filed April 4,

This invention relates to double lift jacks and the like.

The primary object of this invention is to provide a jack having a low initial height with a large amount of lifti Such a jack e Figure l is a side elevation of the jack' in raised position and showing the side of the housing removed;

Fig. 2 is a front elevation of the same; Fig. 3 is a horizontal section on the line 3-3 of F ig. 1;

Fig.- 3 s a similar section showing a modified form of the device;

Fig 4 is a section onvthe line 4-4 of Figsl 5 and 6 are vertical sections on the line 5 and 6 respectivelylof Fig. l;

Fig. 7 is a top plan view of the retaining pawl; and

8 is a similar View of the lifting The embodiment illustrated comprises a .housing 10 in which is slidably mounted a vertical lift-ing member 11, the latter being of U-shaped'cross section as shown in Fig. 3, and *hav' a second lifting member 12 slidable therem.

Both these members 11 and 12 have similarly formed teeth 13 and 14 for-med thereon respectively. These teeth are in registra tion so that when the lifting member 12 is within the U-shaped member 11, both sets of teeth will be engaged by the pawl 15 which is pvotally mounted on the pin 16.

An Operating member 17 is also pivotally mounted on the pin 16 and is operated by a removable handle 18, the lower end of the member 17 has a pawl 19 pivotally mounted on a pin 20. This pawl, as shown in Fig.

8, has two engaging edges 21 and 22, the former projecting beyond the edge 22 so that when the inner member 12 is in front of this pawl, the pawl will engage only the teeth of the rack 12 so that only the inner member 12 will be lifted.

During the earlier stages of the lifting 1924. Serial No. ?04,175.

operation the member 11 will be entirely enclosed within the housing 10. This member has a retaining pawl 23 pivotally mounted on "a pin 24. This pawl 23 which is operated by gravity, engages the teeth of the rack 12 as this rack is lifted by the tooth 21 of the lifting pawl 19. 4

As soon, however, 'as the lowermost tooth of the rack 12 is passedpthe pawl 19 is forced inwardly by the spring-; 25, tooth 21 being forced under member 12 into. the channel of member 11, and the teeth then engage the teeth 13 of the U-shaped member 11, causing the latter to be lifted. It is then retained by the pawl 15.

Figure 1 shows a well known form of releasing n'echanism having a lever 26 which is pivotally mounted on a pin 27 and operates on the flat spring 25.

Thus it will be seen that the total lift of the jack isconsiderably greater than the height of the jack when lowered.

In lowering the jack from the position shown in Fig. 1, the outer end of the reversing lever 26 is lowered toward the member 17, until it strikes the opposite end of the slot in which it operates. This lowering of member 26 relieves the tension`of spring 25, and loosens the effective coupling between pawls 15 and 19, thereby permitting pawl 19 to pass over a tooth 13 or 14 as said pawl is raised but forcing said pawl into engaement with the next succeeding tooth 13. raising thejack handle 18 the retaining pawl 15 is held away from the teeth 13 until the upward limit of the stroke is being reached when the tightening of spring causes it to again move into engagement with the tooth 13 next above the one previously engaged. During' 'this raising of handle 18 racks 11 and 12 have been descending with pawl 19'.

Thus it will be seen that lifting members or racks 11 and 12 have been maintained in the relative position shown while descending, until the tooth 21 of the lift-ing pawl passes under the 'lower-most tooth 'ofthe rack of the upper lifting member 12. From this point on down the tooth 21 engages'only the teeth 14 which serve to hold the lateral teeth of the pawl 19 out of engagement with the racks 13. v

Immediately after the tooth 21 engages the lowermost tooth of the rack 14 the lower end of the pawl 23 engages a pin-28 in the housing, thereby causing the pawl 23 to be thrown out of engagement with the teeth of the lifting member 12 andholding the pawl 23 out of engagement during the time the lifting memberll is within the hous- Fig. 3' is shown a modified form of the device havingtwo lifting members 11 and 12' which act in substantially' the same way except that the member 11 has teeth only on one side instead of both as` shown in hile I have shown and described certan embodiments of my invention, it is to be understood that it is capable of many modifications. Changes therefore in the con- `struction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims, in which it is my intention to claim all novelty inherent in my invention as broadly as possible in view of the prior art.

I claim: 1. A lfting jack comprising a base, two

- telescoping liftng membersslidable in the base, the. outer of said members being U- 'shaped, the inner member substantially filling the U-shaped, groove therein, registering ratchet teeth on the front of said members, a ratchet" pawl, a retainin pawl, Operating on said teeth, the teeth o the innermember serving to hold the ratchet pawl out of engagement with the teeth of the outer member until said inner member is raised a predetermined amount.

2. A lifting jack comprising a base,`two telescoping liftng members slidable in the base, the outer of said members being U- shaped the inner member substantiallyfilling the U-shaped groove 'therein, registering ratchet teeth on the front of said members, a double ratchet pawl having a finger ada ted to make contact with the ratchet teet of the' inner member until said member is -lifted`; iedeternined amount and a second finger back of the line of the first mentioned finger adapted .to make. contact with the teeth of the outer member when `base, the outer of said members being adapted to make contact with the ratchet teeth of the inner member until said mem ber is lifted a predetermined 'amountand a second' finger back of the line of the first -mentioned finger adapted to make contact with the teeth of the outer member when the inner member is raised above said point, lever-operated means for moving said pawl, a pawl for retaining the outer member, and a pawl carried by the outer member and adapted to engage the teeth of the inner member for retaining it in raised position.

4. A lifting jack comprising a base, two

telescoping liftingmembers slidable in the v base, the outer of said members being U- shaped the inner member substantiall'y filling the U-shaped groove therein, registering ratchet teeth on the front of said members, a double ratchet 'pawl *having a finger adapted to make contact with the ratchet teeth of the inner member until said memberis lifted a predetermined amount and a second finger back of the line of the first mentioned finger adapted to make contact with the 'teeth of the outer member when' the inner member is raised above said point, lever-operated means for moving said pawl, a pawl. for retaining the outer member, `a pawl carried by the outer member and a'dapted to engage the teeth of the inner' member for retaining it in raised position, and means for releasing the last-mentioned pawl when the. members are returned to a predeterminedposition.

JOHN w. BATE. i 

